I Accidentally Transmigrated into a Book, and Now I'll Rewrite the Ending

The author, furious over the ending of a tragic romance novel, unexpectedly wakes up inside the story as the little sister of a background character who appeared only twice. The male lead walks into the wrong room, and the tragic romance begins… If they want angst, then let’s give them angst. If the male lead and his moonlight-white-girl want to show off their love, let’s make them regret it. If the wicked mother-in-law wants to impose house rules, then let’s indulge her. If the younger sister-in-law wants to stir up trouble, fine, let’s make it a big one. But then the background character’s little sister realizes something is wrong. Why has the male lead in this tragic romance developed a simp complex? She reaches out and pushes him away. “Move aside, you domineering simp. We’ll keep up the angst in a bit. I want to see who that handsome guy behind you is.” How will it all end? The author will decide…